Screw propeller



Sapt. 17, 1940. o. BRocKHAus SCREW PROPELLER Filed March 7, 1939INVENTOR. O/fa 5r X46006 5 ATTORNEY}.

Patented Sept. 17, 1940 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to propulsion devices, and more particularly tothat character of propeller used for marine vessels, the object ofwhich, generally stated, is the provision of novel 5 devices superior tothose heretofore designed both from the point of efliciency in operationand serviceability over extended periods of use.

The invention has for a particular object the provision of a pluralityof propeller blades so interconnected over a projected arc of thesupportporting hub periphery therefor as to overcome possibility ofwarping from axial thrust characteristics of the blades.

A further object of the invention in such disposition of the blades isthe accommodation to overlapping relationship affording extensive thrustareas axially projecting the range within which the propulsive activityof the blades is constantly maintained upon each given mass of waterencountered in the vessels travel. More particularly, said blades are soarranged with respect to one another as to intercept the heretoforecommon retarding dead wash from a preceding blade, the curvature of eachblade moreover, be-

ing designed to direct the encountered water in a relative centripetalaction rearwardly of the vessel rather than centrifugally outwardly withits consequent development of a suctional attraction axially of thedriving tail shaft. I

A further object, in the elimination of the consecutive thrust actionsimparted by blades individually as heretofore designed, is the provisionof a propeller assembly acting more as a unit to equalize the driveactivity throughout the 360 circumference, overcoming strains andobviating the pronounced vibration heretofore conducted through thesupporting tail shaft to the engine andthe vessel.

The invention consists in the novel construc- 40 tion, the adaptationand in the arrangement and combination of parts as hereinafter describedand claimed.

In the drawing- Figure 1 is an end elevation of a propellerrepresentative of a preferred embodiment of the present invention.

Fig. 2 is a side elevation illustrating said strucfor rotation withinthe stern bearing l0.

for the propeller assembly, said shaft mounted H indicates theconventional packing gland. Suchv foregoing structure may be of suitableor well known construction.

Having more especial reference to the present invention, I provide,supported about a relatively elongated hub or nave 20, said naveslidably keyed over the terminal projection [3 of the tail shaft 9 andengaged by the clamping nut l4 thereon, a 10 series of propeller bladesdesignated as "2 l, 22 and 23, each of which is conformed to a generalparabolic plan configuration, the outer extremities of each blade beingdisposed in planes at angularities of approximately 60 from thelongitudi- 15 nal and the inner edges being relatively elongatedlongitudinally and joining the nave over arcs exceeding 240 thereof,said inner edges having an elevational development approximating acubical parabola with the curvilinear leading and rear 20 edges 24, 25being curved to merge, or approximately merge, with planes taken throughthe longitudinal axis of the hub.

More particularly, each of said inner hubward edges 24, 25 of the bladesis configured with re- 25 spect to the nave to terminate at or beyond aradial line taken medially through an adjacent blade, with the width ofeach blade approximating the height of the same.

In its operation, the leading terminals of the 30 blades tend to knifeinto the water as distin-- guished from the hard bite characterizing theconventional propeller and, following this knifing penetration, thewater tends more or less to hug the worm grooves Which lie between theblades in that the particular form of the latter tends to an axialthrust and greatly minimizes the centrifugal throw of the ordinaryblade. Stated otherwise, the water which is propelled longitudinallyalong the nave is very dense with a 40 substantial elimination of airbubbles and, therefore, is a more effective thrust agency. Particularlynoticeable in the use of the propeller is the elimination of thecustomary vibratory hammer, attributed to the fact that each of the 45 Iblades is carried substantially about the entire circumference of thenave with a configuration such that the identical curve characterizingthe forward half of each blade is reversely applied to the rear half ofthat blade, thereby arriving at a blade balance as well as a navebalance. In point of fact, it is found that a relatively steady drive isobtained even though a portion of the propeller clears the water.

Attention is directed to the theories propounded by numerous scientificauthorities in re the desired activity of a propeller construction, moreparticularly with respect to the disadvantages in repelling theencountered water centrifugally rather than in planes parallel to thehub axis. In this particular, the inventor recognizes the theoreticalconstruction of the screw propeller designed by Hugh Keitel, for whichU. S. Patent No. 1,095,732 was issued May 5, 1914, improvements over thesame, however, being considered obvious.

While illustrating and specifically describing the now preferredembodiment of the invention, minor structural alterations might be madewithout departing from the spirit of the invention and I accordinglyconfine myself only as limited by the scope of the hereto annexed claim.

What I claim is A screw propeller comprising a nave and a plu- 20 ralityof blades of which the outer edge of each blade, viewed from the end aswell as from the side of the propeller, is generally parabolic and ofwhich the root edge of each blade, viewed from above, occupies the lineof a sinusoid curve, the leading terminal of each of said root edgesgenerally coinciding with the front-end limit of the nave and meetingthe latter approximately in the plane of the longitudinal axis of thepropeller and of a radial line taken medially through the precedingblade, the rear terminal of each of said root edges generally coincidingwith the rear-end limit of the nave and meeting the latterapproximatelyin the planeof the longitudinal axis of-the propeller andof a radial line taken medial- 1y through the succeeding blade, saidparabolic figures defined by the outer edges of the blades, consideredboth in end and side elevation, being such that the curve produced atone side of the major axis of each parabola reversely corresponds to thecurve produced at the other side of the major axis.

OTTO BROCKHAUS.

